How many pairs of ear ossicles are there? | Socratic How many pairs of ear ossicles are there? Start with a one sentence answer Then teach the underlying concepts Don't copy without citing sources Write a one sentence answer... Answer: I want someone to double check my answer Describe your changes (optional) 200 Cancel 3 pairs. Each ear has three ossicles : Malleus, Incus, Stapes. Explanation: There are three ossicles in each ear : Malleus, Incus, Stapes. As we have a pair of ears, so in total there are 6 ossicles, or 3 pairs of ossicles. This diagram shows a section through ear. We can see the ear ossicles inside the middle ear. Was this helpful? Let the contributor know! Yes How many bones are there in the ear? | Reference.com How many bones are there in the ear? A: Quick Answer There are three bones in each ear, and they're some of the tiniest bones in the human body. These bones are found in the middle ear and are called the ossicles.

Full Answer The three ossicles are named the incus, stapes and the malleus, and they're named for the shape they have. They are also known as the anvil, stirrup and hammer. The ossicle bones are all linked together to make sound possible. These three bones work together to move and transmit sound to the inner ear. Fluid membrane waves are created by the bones to convert the eardrum's compression sound waves. Bones of the Ear - Anatomy Pictures and Information Home > Skeletal System > Bones of the Head and Neck > Bones of the Ear Bones of the Ear The bones of the ear, also known as the auditory ossicles, are the three smallest bones in the human body. These bones play an important role in the sense of hearing by transmitting sounds to the inner ear. Anatomy The three auditory ossicles – the malleus, incus, and stapes – are tiny bones found in the middle ear.

Each bone is named in Latin for its shape: Malleus means hammer or mallet Incus means anvil Move up/down/left/right: Click compass arrows Rotate image: Click and drag in any direction, anywhere in the frame Identify objects: Click on them in the image 2D Interactive 3D Rotate & Zoom Change Anatomical System Full Bones of the Ear Description [Continued from above] . . . The hammer-like malleus is the most lateral of the ossicles and has a large, rounded head on its superior end, which tapers to a narrow neck and handle on its inferior end. It is connected to the tympanic membrane, or eardrum, at the handle and forms a synovial joint with the incus at the head. The anvil-like incus is the middle ossicle that forms synovial joints with the malleus on its lateral side and the stapes on its medial side. The incus is widest where it meets the malleus and tapers to a thinner projection known as the lenticular process where it meets the stapes. The stirrup-shaped stapes is the smallest ossicle with a hollow space in the middle.

The stapes begins with a tiny cylindrical head where it meets the incus before splitting into two parallel columns of bone known as the anterior and posterior crus. These columns end suddenly at the flat, oblong base that rests within the oval window and conducts sounds into the inner ear. Physiology The main function of the auditory ossicles is the conduction of sounds to the inner ear where they transduced into nerve signals and sent onward to the brain. Sound waves entering the ear pass through the auditory canal of the outer ear and trigger vibrations in the tympanic membrane. These vibrations are conducted into the malleus, which is connected to the tympanic membrane through its handle region. The malleus conducts its vibrations into the incus through its synovial joint and the incus likewise conducts vibrations into the stapes. Finally, the vibrations of the stapes push its base back and forth through the oval window to form new waves in the endolymph of the inner ear. The secondary function of the auditory ossicles is the attenuation of sound waves to control the volume of sounds reaching the inner ear.

A pair of skeletal muscles, the tensor tympani and stapedius, contract to reduce the vibration of the malleus and stapes in response to loud sounds. Sound attenuation is very important in daily life by limiting the sounds produced during chewing and the sound of one’s own voice while talking. Prepared by Tim Taylor, Anatomy and Physiology Instructor The Ossicles and Their Function The Ossicles The three tiniest bones in the body form the coupling between the vibration of the eardrum and the forces exerted on the oval window of the inner ear . Formally named the malleus, incus, and stapes, they are commonly referred to in English as the hammer, anvil, and stirrup. With a long enough lever, you can lift a big rock with a small applied force on the other end of the lever. The amplification of force can be changed by shifting the pivot point. The ossicles can be thought of as a compound lever which achieves a multiplication of force. This lever action is thought to achieve an amplification by a factor of about three under optimum conditions, but can be adjusted by muscle action to actually attenuate the sound signal for protection against loud sounds.

A physiology book describes the ossicles as small enough to fit collectively on a U.S. dime. The image to the right actually makes the ossicles a bit too large - they may be half that large in some persons. The Total Number of Bones in the Human Body The Total Number of Bones in the Human Body What are the total number of bones in the human body? How many bones are there? Picture showing the number of bones in the full-grown human body. Infants have over 270. Most agree that an adult, full-grown human has 206 distinct bones. However, this number may vary to a slight degree depending on individual interpretation. For example, some sources indicate that there are 208 bones if you consider the three sternum sections. The problem is that depending on how much the bones have fused together it may be difficult to actually distinguish three sternum bones. Since they are not always distinguishable in a large number of cases its best to count the sternum as just one bone. Therefore, you arrive at 206 bones and not 208. Variation also exists with the sacrum and coccyx so it's best to just count each as one.

The number of bones in small children From the moment we are born our cranial bones begin to ossify (join together and become set). They begin interlocking at the sutures by about the age of two. That is why babies and small children will begin life with more bones in their bodies (over 270) compared to a full-grown adult. As you grow your bones begin to fuse together and that's how you end up with fewer bones in adulthood. Bones continue to grow even past the age of twenty. This is primarily the case for the facial region due to the continued emergence of teeth. Fun Fact: Human Osteology = The study of bones and teeth. The purpose of bones The skeleton forms the framework for the human body and performs some very important functions like support (provides a framework for the body), protection (covers vital organs, e.g. sternum, ribs), hematopoiesis (vital role in generating blood cells) and storage (stores minerals the body needs). The skeleton is held together by flexible tissues consisting of cartilage and ligaments. Bone Names The Auditory Ossicles - Human Anatomy FIG. 918 A. Left stapes. B.

Base of stapes, medial surface. Articulations of the Auditory Ossicles (articulationes ossiculorum auditus).The incudomalleolar joint is a saddle-shaped diarthrosis; it is surrounded by an articular capsule, and the joint cavity is incompletely divided into two by a wedge-shaped articular disk or meniscus. The incudostapedial joint is an enarthrosis, surrounded by an articular capsule; some observers have described an articular disk or meniscus in this joint; others regard the joint as a syndesmosis. Ligaments of the Ossicles (ligamenta ossiculorum auditus).The ossicles are connected with the walls of the tympanic cavity by ligaments: three for the malleus, and one each for the incus and stapes. The anterior ligament of the malleus (lig.

mallei anterius) is attached by one end to the neck of the malleus, just above the anterior process, and by the other to the anterior wall of the tympanic cavity, close to the petrotympanic fissure, some of its fibers being prolonged through the fissure to reach the spina angularis of the sphenoid. The superior ligament of the malleus (lig. mallei superius) is a delicate, round bundle which descends from the roof of the epitympanic recess to the head of the malleus. The lateral ligament of the malleus (lig. mallei laterale; external ligament of the malleus) is a triangular band passing from the posterior part of the notch of Rivinus to the head of the malleus. Helmholtz described the anterior ligament and the posterior part of the lateral ligament as forming together the axis ligament around which the malleus rotates. The posterior ligament of the incus (lig. incudis posterius) is a short, thick band connecting the end of the short crus of the incus to the fossa incudis.

A superior ligament of the incus (lig. incudis superius) has been described, but it is little more than a fold of mucous membrane. The vestibular surface and the circumference of the base of the stapes are covered with hyaline cartilage; that encircling the base is attached to the margin of the fenestra vestibuli by a fibrous ring, the annular ligament of the base of the stapes (lig. annulare baseos stapedis). The Muscles of the Tympanic Cavity (musculi ossiculorum auditus) are the Tensor tympani and Stapedius. The Tensor tympani, the larger, is contained in the bony canal above the osseous portion of the auditory tube, from which it is separated by the septum canalis musculotubarii. It arises from the cartilaginous portion of the auditory tube and the adjoining part of the great wing of the sphenoid, as well as from the osseous canal in which it is contained.

Passing backward through the canal, it ends in a slender tendon which enters the tympanic cavity, makes a sharp bend around the extremity of the septum, and is inserted into the manubrium of the malleus, near its root. It is supplied by a branch of the mandibular nerve through the otic ganglion. FIG. 919 Chain of ossicles and their ligaments, seen from the front in a vertical, transverse section of the tympanum. (Testut.) The Stapedius arises from the wall of a conical cavity, hollowed out of the interior of the pyramidal eminence; its tendon emerges from the orifice at the apex of the eminence, and, passing forward, is inserted into the posterior surface of the neck of the stapes. It is supplied by a branch of the facial nerve. Actions.The Tensor tympani draws the tympanic membrane medialward, and thus increases its tension.

The Stapedius pulls the head of the stapes backward and thus causes the base of the bone to rotate on a vertical axis drawn through its own center; the back part of the base is pressed inward toward the vestibule, while the forepart is withdrawn from it. By the action of the muscle the tension of the fluid within the internal ear is probably increased. The Mucous Membrane of the Tympanic Cavity is continuous with that of the pharynx, through the auditory tube. It invests the auditory ossicles, and the muscles and nerves contained in the tympanic cavity; forms the medial layer of the tympanic membrane, and the lateral layer of the secondary tympanic membrane, and is reflected into the tympanic antrum and mastoid cells, which it lines throughout. It forms several vascular folds, which extend from the walls of the tympanic cavity of the ossicles; of these, one descends from the roof of the cavity to the head of the malleus and upper margin of the body of the incus, a second invests the Stapedius muscle: other folds invest the chorda tympani nerve and the Tensor tympani muscle.

These folds separate off pouch-like cavities, and give the interior of the tympanum a somewhat honey-combed appearance. One of these pouches, the pouch of Prussak, is well-marked and lies between the neck of the malleus and the membrana flaccida. Two other recesses may be mentioned: they are formed by the mucous membrane which envelops the chorda tympani nerve and are situated, one in front of, and the other behind the manubrium of the malleus; they are named the anterior and posterior recesses of Troltsch. In the tympanic cavity this membrane is pale, thin, slightly vascular, and covered for the most part with columnar ciliated epithelium, but over the pyramidal eminence, ossicles, and tympanic membrane it possesses a flattened non-ciliated epithelium. In the tympanic antrum and mastoid cells its epithelium is also non-ciliated.

In the osseous portion of the auditory tube the membrane is thin; but in the cartilaginous portion it is very thick, highly vascular, and provided with numerous mucous glands; the epithelium which lines the tube is columnar and ciliated. Vessels and Nerves.The arteries are six in number. Two of them are larger than the others, viz., the tympanic branch of the internal maxillary, which supplies the tympanic membrane; and the stylomastoid branch of the posterior auricular, which supplies the back part of the tympanic cavity and mastoid cells. The smaller arteries arethe petrosal branch of the middle meningeal, which enters through the hiatus of the facial canal; a branch from the ascending pharyngeal, and another from the artery of the pterygoid canal, which accompany the auditory tube; and the tympanic branch from the internal carotid, given off in the carotid canal and perforating the thin anterior wall of the tympanic cavity. The veins terminate in the pterygoid plexus and the superior petrosal sinus.

The nerves constitute the tympanic plexus, which ramifies upon the surface of the promontory. The plexus is formed by (1) the tympanic branch of the glossopharyngeal; (2) the caroticotympanic nerves; (3) the smaller superficial petrosal nerve; and (4) a branch which joins the greater superficial petrosal. The tympanic branch of the glossopharyngeal (Jacobsons nerve) enters the tympanic cavity by an aperture in its floor close to the labyrinthic wall, and divides into branches which ramify on the promontory and enter into the formation of the tympanic plexus. The superior and inferior caroticotympanic nerves from the carotid plexus of the sympathetic pass through the wall of the carotid canal, and join the branches of the tympanic branch of the glossopharyngeal. The branch to the greater superficial petrosal passes through an opening on the labyrinthic wall, in front of the fenestra vestibuli.

The smaller superficial petrosal nerve, from the otic ganglion, passes backward through a foramen in the middle fossa of the base of the skull (sometimes through the foramen ovale), and enters the anterior surface of the petrous part of the temporal bone through a small aperture, situated lateral to the hiatus of the facial canal; it courses downward through the bone, past the genicular ganglion of the facial nerve, receiving a connecting filament from it, and enters the tympanic cavity, where it communicates with the tympanic branch of the glossopharyngeal, and assists in forming the tympanic plexus. The branches of distribution of the tympanic plexus are supplied to the mucous membrane of the tympanic cavity; a branch passes to the fenestra vestibuli, another to the fenestra cochleæ, and a third to the auditory tube. The smaller superficial petrosal may be looked upon as the continuation of the tympanic branch of the glossopharyngeal through the plexus to the otic ganglion. In addition to the tympanic plexus there are the nerves supplying the muscles.

The Tensor tympani is supplied by a branch from the mandibular through the otic ganglion, and the Stapedius by a branch from the facial. The chorda tympani nerve crosses the tympanic cavity. It is given off from the sensory part of the facial, about 6 mm. before the nerve emerges from the stylomastoid foramen. It runs from below upward and forward in a canal, and enters the tympanic cavity through the iter chordæ posterius, and becomes invested with mucous membrane. It traverses the tympanic cavity, crossing medial to the tympanic membrane and over the upper part of the manubrium of the malleus to the carotid wall, where it emerges through the iter chordæ anterius (canal of Huguier). Ear Ossicles 2. Incus (anvil) 3. Malleus (hammer) The auditory ossicles consist of three small bones found within a space (the tympanic cavity) in the temporal bone of the skull. The bones (which are named for their shape) are connected by synovial joints.

Resting against the oval window of inner ear is the stapes (stirrup), which articulates with the middle ossicle called the incus (anvil). The incus articulates with the malleus (hammer), whose "handle" is attached to the internal surface of the tympanic membrane (eardrum). Sound-induced vibrations of the tympanic membrane are thereby amplified and transmitted through these ossicles to the inner ear where they are interpreted as sound. How The Ear Works | The Recording Studio In Your Head We'll start our study of the ear by looking at Figure 1, top right. This drawing shows the morphology of the ear, as usually represented. This is divided into three sections. The outer ear consists of the auditory canal and the exterior of the tympanic membrane, better known as the eardrum. The malleus, incus and stapes, which are small bones often referred to as ossicles, belong to the middle ear, along with the interior of the tympanic membrane. Then there is the inner ear, which includes the cochlea and the semicircular canals. Last, we find two nerves that connect the ear to the brain.

(The semicircular canals and vestibular nerves don't relay any information relating to hearing; their purpose is to give us a sense of gravity and balance, so we'll leave them aside.) Figure 1: The morphology of the human ear (diagram derived from Chittka L, Brockmann A (2005): Perception Space — The Final Frontier, ). What we call 'sound' is in fact a progressive acoustic wave — a series of variations in air pressure, spreading out from whatever source made the sound. When these pressure variations strike the ear, they find their way through the external auditory canal to the tympanic membrane, setting it into vibration. The signal is thus converted to mechanical vibrations in solid matter. These vibrations of the tympanic membrane are transmitted to the ossicles, which in turn transmit them to the cochlea. Here the signal undergoes a second change of nature, being converted into pressure variations within liquid. These are then transformed again by specialised hair cells, which convert the liquid waves into nervous signals. This extraordinary signal path encompasses four distinct states of information: acoustic, mechanical (solid), mechanical (liquid), and electric, more specifically electro‑chemical. The very nature of the information also changes: from analogue, it becomes digital.

Really! Whereas mechanical information propagation is analogous to the original sound wave, the nervous signal is even more decorrelated from the sound wave than AES‑EBU audio signals can be. Put simply, the ear includes a built‑in analogue‑to‑digital converter. Figure 2, right, summarises these changes of state and nature in the sound information. Figure 2: A complex set of audio devices! The Outer Ear: EQ & Compression Besides such changes in state and nature, the audio signal is also subject to important changes in content. It is, in short, rather heavily equalised and compressed. Let's begin with the external auditory canal, which has the shape of a shallow tube. Now, as I explained in a previous SOS article ( /sos/sep10/articles/convolution.htm ), reverb in a very small space is so short that it's perceived as EQ, rather than as ambience. The reverberation of the auditory canal boosts frequencies around 3kHz by 15 to 20dB. At this point, the signal is transformed into mechanical vibrations by the eardrum, which also acts as an EQ. To understand why, compare it to an actual drum.

Strike a timpani and it will resonate at certain frequencies, which are inversely proportional to the size of the instrument. Strike a snare drum and, being much smaller, it will resonate at higher frequencies. Strike an eardrum, and it resonates at even higher frequencies, thus filtering the input signal correspondingly. The tympanic membrane is also attached to a muscle called the tensor tympani. When confronted with high sound pressure levels, this muscle contracts, heavily damping eardrum movements. It is, in other words, a mechanical compressor/limiter, allowing low‑level vibrations through unaltered, but damping larger vibrations. The Middle Ear: EQ, Compression & Impedance Matching Behind the eardrum, we find the ossicles. The purpose of these minute bones is to convert the eardrum vibrations into pressure variations in the cochlear fluid. Now, converting acoustic waves into variations in fluid pressure is no easy matter — look at what happens when you've got water in your ears. This means that conversion of acoustic waves from air to water is anything but efficient. Put differently, fluids have a high input impedance when receiving acoustic waves.

The ear's answer to the problem is simple: give me a lever and I can move the earth! To override this high input impedance, the ossicles form a complex system of levers that drastically increase pressure variations from the eardrum to the entrance of the inner ear. This is made possible physically by the fact that the eardrum is 20 times the size of the cochlear window. It really works as a conventional lever does: low pressure across a wide area is converted into higher pressure on a small area. Dealing with impedance matching with a system of levers as complex as the ossicles doesn't come without side‑effects. The ossicles' frequency response is not flat, turning them into another EQ. In this case, frequency response is decent around 0.5kHz, gets even better near 1-2kHz, and then degrades steadily above this frequency. The ossicles also serve as compressor/limiter, thanks to what's called the stapedian muscle. Like the tensor tympani in the case of the eardrum, the stapedian muscle stabilises the ossicles at high levels. The middle ear also contains the eustachian tube.

Now, the purpose of this is simple: seal the opening at the rear of a kick drum, and you suddenly get much less sound! Likewise, if you seal the cavity behind the eardrum, you suddenly have problems hearing properly. This happens regularly; for example, when we're on an airplane or when we get a cold. In both cases, the eustachian tube gets clogged, and that prevents the tympanic membrane from moving as it should. The Inner Ear: Multi‑band Compression, Pitch Tracking & ADC By now, the audio signal has reached the inner ear, and that means the cochlea. This snail‑shaped organ is filled with liquid. Logically enough, it must be waterproof, in order to prevent any fluid leaking. This explains the purpose of the round window, a small, elastic membrane on the surface of the cochlea. Its purpose is to allow movement of the fluid inside the cochlea. Liquids are incompressible, and without this membrane, the fluid enclosed inside the cochlea would completely block the ossicle movements. Indeed, stiffening of the oval window can lead to hearing losses of about 60dB.

Inside the cochlean we find the tectorial membrane, which moves along with the pressure variations of the cochlear fluid. As shown in Figure 3, above, this membrane is in contact with the cilia on the top of the hair cells. There are two kinds of hair cells. The outer hair cells are the actual receptors. When the tectorial membrane moves, so does the hair on the the outer cells. This movement is then encoded into electrical digital signals and goes to the brain through the cochlear nerve. The inner cells have a different role: when the audio signal gets louder, they stick themselves to the tectorial membrane in order to limit its movements, playing the role of another dynamic compressor. Figure 3: Inside the cochlea. This tectorial membrane exhibits a clever design. Its stiffness is variable, and decreases gradually towards the center of the 'snail'. This is a way of tuning the membrane to different frequencies. In order to understand the phenomenon, consider guitar tuning. When you want pitch of a string to be higher, you stretch it so it gets more tense, and stiffer. Generally speaking, stiffer materials are able to vibrate at higher frequencies.

This makes the tectorial membrane a bank of filters, with an important result: outer cells are frequency‑specific, each group of cells being dedicated to particular frequencies. Also consider the inner cells, and their ability to attenuate the tectorial membrane's movement. They function as a frequency‑specific compressor — in other words, a multi‑band compressor! The tectorial membrane's decreasing stiffness towards its end serves another important purpose, which is frequency tracking. A particular audio frequency will set the membrane in motion at a particular position, and that vibration will be sensed by a specific set of outer cells. A comparatively lower frequency will set the membrane in motion closer to the centre of the 'snail', and that vibration will be sensed by another set of outer cells. The brain, by analysing which set of outer cells was put in motion, will then be able to tell that the second frequency was the lower one. Notice how, during this process, the tectorial membrane really acts in the manner of a filter bank, performing an actual spectral analysis of the input signal. Figure 4, below, illustrates the rough position of a few key frequencies on the cochlea. Figure 4: Filter bank frequencies on the cochlea.

Harmonic sounds come as a set of regularly spaced pure tones: if the fundamental frequency is 100Hz, the harmonic frequencies will be 200Hz, 300Hz, 400Hz and so on. As shown in Figure 5, each one of those frequencies will correspond to a particular area of the tectorial membrane. Suppose a given harmonic sound comes with its fundamental frequency plus nine harmonics. In this case, no fewer than 10 distinct areas of the tectorial membrane will be set in vibration: this provides an abundance of coherent information to the brain, which will have no difficulty in quickly and easily finding the right pitch. This is what makes the human ear so powerful for pitch identification. Figure 5: Pitch tracking inside the cochlea. With the hair cells, we come to the end of the audio path inside the ear. Hair cells are neurons, and the purpose of the outer hair cells is to convert the mechanical vibrations that come from their cilia into nerve signals. Such signals are binary (all or nothing), and seem to be completely decorrelated from the analogue signals to which they correspond.

In other words, they're digital signals, and the inner hair cells are analogue‑to‑digital converters. What's It All For? There is no denying that the ear is quite a complicated device, with a lot of processing built in. We've met no fewer than four EQs and three compressors. Are those really necessary? And what can be their purpose? Let's begin with the built‑in compressors. They're not always active. In a quiet ambience, none of them is functioning. The louder the audio signal that gets to the ear, the more the compressors do to attenuate the audio signal that gets to the outer hair cells. This enables the human ear to withstand a dynamic range of roughly 140dB, which corresponds to a ratio of 100,000,000,000,000:1 between the loudest and the quietest sounds we can perceive. Considering we're dealing with three tiny mechanical compressors, that's no mean feat. The actions of the equalisers are also far from accidental.

If you refer back to the above descriptions, you will notice that the frequency values that get boosted are centred around 1-3kHz, while additional processing inside the cochlea adds a strong gain near 4kHz. Those frequencies correspond to the part of speech that's linked to understanding, so EQs in the ear make us more able to communicate with each other. Oral communication being an extremely important aspect of homo sapiens behaviour, we can safely assume that we're dealing with Darwinist EQs. What About The Bass? Naturally enough, the way the ear works has huge consequences for how we perceive music — and for how we make it. Take the EQs inside the ear: we've seen that they privilege the frequencies around 0.5‑4kHz. Those three octaves contain the frequencies we are most sensitive to. And, naturally enough, they are the ones most favoured by musicians and composers, consciously or not. Think about it: how many concertos for violin have been written, and how many for double bass? How many for trumpet, and how many for tuba? In more modern applications, consider the kick drum in a mix.

If you want it to be heard, you have to boost the medium‑high frequencies that are present in the attack. The same goes for the electric bass: if you want it to be completely drowned inside a mix, remove the medium‑high frequencies! It's as simple as that. To make bass instruments clear and audible, you need to make sure the mid-range frequencies are in place. Low frequencies themselves are clearly useful — they can convey roundness, body, strength, and so on — but any part of the musical language linked to understanding, anything that requires sensitivity, needs to be inside or near the 0.5‑4kHz range. For an example, think about music being played through a telephone. Telephones usually degrade considerably anything outside the 0.5‑4kHz range. Sure, music through a telephone is ugly, but the essential message of the music remains intact: it's easy to recognise the song, and you have no trouble hearing the different instruments. By contrast, try listening to music through a 100‑400Hz band‑pass filter.

This is still a three‑octave‑wide filter — as wide as a 0.5‑4kHz in terms of logarithmic frequencies — but it makes music completely incomprehensible. It becomes very hard to recognise any of the instruments, and the message is completely lost. Before the advent of the studio, this 0.5‑4kHz constraint was not so much of an issue, because most instruments operate within this frequency range anyway. With electroacoustic music — and that includes many kinds of pop music nowadays — one must be more careful. The 0.5‑4kHz range should contain the most important part of the message. To carry the essence of your music, forget about those bass frequencies, your priority is elsewhere. The same naturally applies to the very high frequencies. Don't try to convey your musical message using the 4‑20kHz range: it's useless.

(This, admittedly, is so obvious that only a handful of unreasonable avant garde composers with a strong tendency to sadism have ever been tempted to write and produce music based mainly on such frequencies.) The 'Ghost Fundamental' Looking back at Figure 5, one observation jumps to mind: together, the harmonics include more information about the pitch of a sound than does the fundamental frequency. There can be as many as 16 audible harmonics, setting 16 zones of the tectorial membrane in motion, whereas the fundamental tone only puts one zone in motion. Not only are the harmonics important, so is the spacing between the harmonics, which is constant, and repeated up to 15 times. Just think how it's so much easier to identify pitch from a 'normal' instrumental sound with harmonics than from a pure sine wave. In fact, the fundamental frequency is so unimportant as far as pitch is concerned that it can simply be removed without any impact on pitch. This experiment was first performed by Pierre Schaeffer during the 1950s. This knowledge is very relevant to music production.

Let's say that you're writing an arrangement for a song and you find yourself fighting frequency overlap in the 100‑1000Hz range. For instance, you've got a sampled brass section that gets in the way of the lead vocals. A straightforward solution would be to equalise the brass section to attenuate the frequencies that neighbour those of the lead vocals. This will probably work, but there is a more radical solution: just remove the fundamentals from the brass samples. The pitch will remain the same, and the frequency overlap problem will be greatly reduced. True, it will alter the brass section timbre, but so would an EQ. Conversely, it's perfectly possible to 'design' whole instrumental sections that appear to be pitched between 100 and 200Hz, whereas in truth this frequency range remains unused. This leaves more room for other instruments, which in turn means more freedom, richer arrangements, and easier mixes. Let's recap and list the ear's built‑in EQs and compressors: External auditory canal: EQ. Ossicles: EQ + compressor. Cochlea: EQ + compressor.

In three cases out of four, dynamic and frequency processing are closely linked, with a fundamental consequence: the timbre of the sound we hear depends on its intensity. In other words, the ear applies a different EQ to incoming audio signals depending on how loud they are. This behaviour is very different from that of a studio EQ, which applies the same frequency gains regardless of input signal level. Now, this is quite natural. Remember that most transducers in the ear are mechanical. They're physical objects that are set into vibration. Obviously, you can't expect a vibrating object to react identically when it's slightly shivering and when it's moving like crazy. This is particularly true of a complex lever system such as the ossicles. It's only common sense that the resonant frequencies will differ. This means that you just can't expect the ear's EQs to apply the same gain whatever the input level — and they don't. When representing the ear's EQ transfer functions, we have to do so for a set of given input levels. See Figure 6, on the previous page, for three transfer functions at different levels. We've assumed, for this graph, that the EQ's gain is always 0dB at 1000Hz.

Those transfer functions are derived from what's called the equal loudness curves, shown in Figure 7. They're far more common, but a bit obscure, and not quite related to the concept of EQ. Figure 6: The equalisation applied in the ear depends on level. Figure 7: The well‑known Fletcher‑Munson, or equal loudness curves. Obviously, the ear's EQ transfer functions are of enormous importance when it comes to mixing. Looking again at Figure 5, what can we read? Consider two tones, one at 60Hz and one at 400Hz, that seem to be equally loud. Reduce the monitoring level by 40dB, and the 60Hz tone will now sound 15dB quieter than the 1000Hz one. To be convinced, listen to a kick drum sample very quietly: you don't hear any bass frequencies. Turn up the volume considerably, and suddenly the same kick drum can be heard with plenty of bass frequencies. This brings an important consequence: imagine you're in the middle of a mix and you're listening to it at quite a high level. Everything is going well, your sound is round and powerful...

Now reduce the monitoring volume: hey presto, no more bass frequencies. Your mix is shallow and anything but powerful. So are you sure you want to mix that loud? Naturally, the same principle applies when you're actually writing the music: if you don't want to be disappointed afterwards, turn the volume down. High monitoring levels are for the consumer, not the producer. And, by the way, notice how this phenomenon entirely confirms what I was explaining above: forget about those bass frequencies, really. They're just not reliable. The choice of a given monitoring level is not trivial. Not only does cranking up the volume change the frequency balance of a mix, but it also changes the pitch. You don't believe it? Try the following experiment. Take a pair of good‑quality headphones, such as Beyerdynamic DT770s or Sennheiser K271s. Use them to listen to some music at high level, then remove the headphones from your head, and place them 10 centimetres in front of your face. You will hear all pitches of the song going down noticeably, by up to half a tone.

This effect is more obvious with certain tracks than others; try it with the chorus from the song 'Circus' by Britney Spears. Now that we know how the ear works, we can suggest an explanation for this phenomenon. When we listen to loud music, all the compressors in the ear swing into action, including tensor tympani and stapedian muscles. The tensor tympani tightens the eardrum, and the stapedian muscle stiffens the ossicles. As we've seen before, when a vibrating object gets more tense, it resonates at a higher pitch. The same applies for the eardrum and ossicles. As a consequence, when audio input gets considerably louder, the whole mechanical part of the ear will resonate at higher frequencies. This prompts a global stimulation offset of the tectorial membrane towards higher frequencies, and confuses the brain into thinking it's listening to transposed musical content. Conclusion As we've seen throughout this article, the ear is a very complicated device, and hearing is a delicate and complex phenomenon. Even if we restrict ourselves to monaural audition, the sense of hearing seems to be at the origin of many illusions.

Perceptual aspects that we generally think of as independent, such as timbre, volume and pitch, are in fact inter‑related. The fundamental frequency of a harmonic sound, the very one we use to define pitch, is actually of no importance at all as far as our perception of pitch is concerned. This should put into perspective the common saying that the ears are the ultimate judge in music production. To some extent they certainly are, but as we are now aware, they can also be fooled extremely easily. The only reasonable suggestion would be prudence. When designing sounds, when mixing, in music and/or ambience production in general, when you want to evaluate what you're doing, take your time. Change your monitoring level, walk to the other end of the studio, listen to your work on other speakers... anything that can stop you fooling yourself. And don't hesitate to use meters, be they loudness meters or spectrograms: true, they show reductive information that is not necessarily related to what we hear, but they cannot be tricked. When writing or producing music, the ease with which the ear is confused can also work to your advantage.

Knowing how the ear works means that you have a head start when it comes to shaping the message you want your listeners to receive! Ear Diseases & Disorders Hearing loss Sometimes facial paralysis Cause: Unknown—but may be more common in adults with history of discharge from ears for long periods of time. Treatment of people with cancer of the middle ear includes surgery and radiation, which targets rays of energy at small areas of cancer cells that might not have been removed during surgery.ï¿½ Otosclerosis Otosclerosis is the buildup of spongy or bone-like tissue in the middle ear that prevents the ossicles, namely the stapes in the middle ear, from working properly.ï¿½ The impaired movement and function reduces the sound that actually reaches the ear. Otosclerosis usually results inï¿½ conductive hearing loss , a hearing loss caused by a problem in the outer or middle ear.

ï¿½ If the buildup of tissue spreads to the inner ear, it is called Cochlear Otosclerosis.ï¿½ This can cause permanentï¿½ sensorineural hearing impairment due to interference with how the nerves in this part of the ear work.ï¿½ Scientists aren’t sure about the exact cause but there is some research suggesting a relationship between otosclerosis and the hormonal changes associated with pregnancy and also with viruses. Treatment for people who are diagnosed with otosclerosis depends on the extent of hearing loss and may include surgery to replace some or all of the ossicles with artificial ones. It is important to discuss the risks and possible complications of this and any procedure, as well as the benefits, with a doctor and a surgeon. If the hearing loss is mild, surgery may not be an option but a properly fitted hearing aid may help some people with otosclerosis. A hearing aid is designed to compensate for a hearing loss by amplifying sound. Mï¿½niï¿½re's diseaseï¿½ Mï¿½niï¿½re's disease affects the inner ear and the vestibular system, which is the system that helps to maintain balance.

In this disease, a part of the cochlea called the organ of Corti becomes swollen, leading to a loss of hearing that may come and go over time. It can also cause severe dizziness, lack of balance, tinnitus (ringing/buzzing sound in the ears), ear pain, and pressure. The disease can exist in mild or severe forms. Approximately 615,000 individuals have been diagnosed with Mï¿½niï¿½re's disease in the United States. Another 45,500 are newly diagnosed each year. Diagnosis is based on symptoms and results of hearing tests. Unfortunately, doctors don’t know what causes Mï¿½niï¿½re's disease, and there is no cure. Researchers think that it may have to do with fluid levels in the inner ear. Treatment for people with Mï¿½niï¿½re's disease includes medicines to help control dizziness and fluid retention in the body, and devices that deliver air pulses to the middle ear. Surgery may also be required. Estimates suggest that 6 out of 10 people will get better on their own or can control the symptoms with diet, drugs, or devices.

ï¿½ Ear Infections Germs such as bacteria and viruses can get into the ear and cause an infection. In particular, the middle ear cavity behind the eardrum can fill up with fluid. Treatment may include managing the pain and taking antibiotics, which are medications that fight infections. Ongoing fluids in the middle ear and ongoing infections over time may cause hearing problems or other difficulties. Otitis Media Infections of the middle ear are one of the most common reasons for children to see a doctor. Three out of 4 children experience ear infection (otitis media) by the time they are 3 years old. Children are more likely to have ear infections like otitis media that come from bacteria or viruses than adults because of their developing ear anatomy. The middle ear is connected to the back of the nose by the auditory tube (also called the eustachian tube) and its location allows easier access to germs. This may lead to a buildup of fluid and pressure, painful infections, and even hearing loss. Infections in children can affect early speech and language development. ï¿½ If the infection is due to bacteria, treatment is possible with antibiotics but if the infection is viral, antibiotics won’t work.

Surgery is another treatment option, especially for children with ongoing infections. Small tubes placed inside of childrens' ears help fluid drainage and relieve pressure in the ears so that hearing improves. Chronic otitis media can affect adults, too. It is a long-lasting middle ear infection that can damage the ossicles (middle ear bones), and even lead to a perforation in the eardrum. Perforations can heal but when a chronic infection is present this is less likely and hearing loss can occur. If you're experiencing hearing difficulties and aren't sure where to turn, schedule a consultation with your local hearing healthcare professional.

Question: How many ossicles are there in each human ear?
Answer: THREE